In Luke Rhinehart's novel The Dice Man, the eponymous hero makes all his decisions by rolling a dice.I can hear any one of my schoolteachers responding to that sentence with "You mean a die. Dice is the plural of die."
Not necessarily, dear teachers.
Die is certainly the preferred singular in AmE, but in BrE one is likely to see dice as both the singular and the plural, even in edited texts like newspapers. A90Six comments on the forum at wordreference.com:
Many people in the UK would not even be aware that die is the singular of dice. Some even believe that when die is written in games instructions it is a typo with a missing c....Better Half disagrees, and says that in his English mind it should be a die and not a dice in the newspaper, but some of my linguistic colleagues have in the past chided me for using die. More evidence that BH spends too much time with Americans? What do you say?
The only time die is really heard is in the expression, "The die is cast," meaning - something has been done or a decision has been made that will now have to run its course and fate will decide the outcome.
The history is a bit convoluted--but both forms have been used in the singular since the 14th century.